Keep bottom pointed objects from falling over in Blender Game Engine
You can use the logic node editor like this on each stump:



Explanation:
At start (Delay node without repeat, Delay = 0) you suspend dynamics (Edit object/Dynamics/Suspend Dynamics)

Then set up a collision node. You must specify the same property for it and the colliding objects! It will activate the restore dynamics and set mass actuators.

So Blender will not calculate dynamics for your stumps until collision. It is a very good performance optimization too. So recommended technique for larger games.